Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Statement [Abstract]
Revenue	$ 11,526	$ 10,550	$ 9,831
Expense:
Compensation and benefits	6,969	6,465	6,182
Other operating expenses	2,919	3,146	2,871
Operating expenses	9,888	9,611	9,053
Operating Income	1,638	939	778
Interest income	28	20	17
Interest expense	(199)	(233)	(241)
Cost of extinguishment of debt	(72)
Investment income (loss)	9	43	(2)
Income before income taxes	1,404	769	552
Income tax expense	422	204	21
Income from continuing operations	982	565	531
Discontinued operations, net of tax	33	306	(290)
Net income before non-controlling interests	1,015	871	241
Less: Net income attributable to non-controlling interests	22	16	14
Net income attributable to the Company	$ 993	$ 855	$ 227
Basic net income per share
- Continuing operations	$ 1.76	$ 1.01	$ 0.97
- Net income attributable to the Company	$ 1.82	$ 1.56	$ 0.43
Diluted net income per share
- Continuing operations	$ 1.73	$ 1.00	$ 0.96
- Net income attributable to the Company	$ 1.79	$ 1.55	$ 0.42
Weighted average number of shares outstanding
- Basic	542	540	522
- Diluted	551	544	524
Shares outstanding at December 31,	539	541	530